How To Find Best Writers?

I have a small floral shop and one of my friend is doing research on the flowers. He has insisted me to write down for him about the best flowers type and to merge his research with my customers and I think it’s a great idea and really unique to get customers attention. Since my friend is already up for the research, I want to hire the professional ghostwriter to get the fascinating writing done also I want to know about the best nonfiction ghostwriter agency that is good and productive in real life story writing task. What do you suggest about this thing and how can I find the best kind of writers?